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Proteins and enzymes

Proteins are made from long chains of smaller molecules called amino acids. These long chains are folded into particular shapes. This is important in relation to how antibodies and enzymes work.

Enzymes are biological catalysts. There are optimum temperatures and pH values at which their activity is greatest. Enzymes are also proteins. If the shape of an enzyme changes, it may no longer work (it is said to have been 'denatured').

Amino acids to proteins

Proteins are polymerspolymer: A polymer is a large molecule formed from many identical smaller molecules (monomers).. They are built up in cells when monomersmonomer: Atom or small molecule that bonds with other monomers to form a polymer eg amino acid monomers forming a protein polymer. called amino acids join together end to end:

Lots of amino acid moleculesa protein molecule

Glycine is an amino acid

Glycine is an amino acid

Alanine is also an amino acid. It has a CH3 group instead of a hydrogen atom

Alanine is also an amino acid. It has a CH3 group instead of a hydrogen atom

There are only about 20 different naturally occurring amino acids. However, each protein molecule [molecule: A molecule is a collection of two or more atoms held together by chemical bonds. It is the smallest part of a substance that displays the properties of the substance. ] has hundreds, or even thousands, of them joined together in a unique sequence. This gives each protein its own individual properties.

Different proteins

The long chains of amino acids fold to give each type of protein molecule a specific shape. Proteins act as:

  • Structural components of tissues (such as muscles)
  • Hormones (such as insulin)
  • Antibodies (part of the body's immune system)
  • Biological catalysts (enzymes)

The particular shape that a protein molecule has allows other molecules to fit into it. This is particularly important for antibodies and enzymes.

Back to Proteins - their functions and uses index

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